Geospatial analysis reveals a hotspot of fecal bacteria in Canadian prairie lakes linked to agricultural non-point sources.

Lakes are sentinels of environmental changes within their watersheds including those induced by a changing climate and anthropogenic activities. In particular, contamination originating from point or non-point sources (NPS) within watersheds might be reflected in changes in the bacterial composition of lake water. We assessed the abundance of potentially pathogenic bacteria (PPB) sampled in 413 lakes within 8 southern Canadian ecozones that represent a wide diversity of lakes and watershed land use. The study objectives were (1) to explore the diversity of PPB; (2) to build a fecal multi-indicator from a cluster of co-occurring PPB; and (3) to predict the fecal multi-indicator over thousands of lakes. We identified bacterial taxa based on 16S rRNA amplicon sequencing and clustered 33 PPB matching taxa in the Canadian ePATHogen database using a Sørensen dissimilarity index on binary data across the sampled lakes. One cluster contained Erysipelothrix, Desulfovibrio, Bacteroides, Vibrio and Acholeplasma and was related to the NPS fraction of agriculture and pasture within the watershed as its main driver and thus it was determined as the fecal multi-indicator. We subsequently developed a fecal multi-indicator predictive model across 200 212 southern Canadian lakes which explained 55.1% of the deviance. Mapping the predictions showed higher fecal multi-indicator abundances in the Prairies and Boreal Plains compared to the other ecozones. These results represent the first attempt to map a potential fecal multi-indicator at the continental scale, which may be further improved in the future. Lastly, the study demonstrates the capacity of a multi-disciplinary approach leveraging both datasets derived from remote sensing and DNA sequencing to provide mapping information for public health governmental policies.

A resistome survey across hundreds of freshwater bacterial communities reveals the impacts of veterinary and human antibiotics use.

Our decreasing ability to fight bacterial infections is a major health concern. It is arising due to the evolution of antimicrobial resistance (AMR) in response to the mis- and overuse of antibiotics in both human and veterinary medicine. Lakes integrate watershed processes and thus may act as receptors and reservoirs of antibiotic resistance genes (ARGs) introduced into the watershed by human activities. The resistome - the diversity of ARGs - under varying anthropogenic watershed pressures has been previously studied either focused on few select genes or few lakes. Here, we link the resistome of ~350 lakes sampled across Canada to human watershed activity, trophic status, as well as point sources of ARG pollution including wastewater treatment plants and hospitals in the watershed. A high percentage of the resistance genes detected was either unimpacted by human activity or highly prevalent in pristine lakes, highlighting the role of AMR in microbial ecology in aquatic systems, as well as a pool of genes available for potential horizontal gene transfer to pathogenic species. Nonetheless, watershed agricultural and pasture area significantly impacted the resistome. Moreover, the number of hospitals and the population density in a watershed, the volume of wastewater entering the lake, as well as the fraction of manure applied in the watershed as fertilizer significantly impacted ARG diversity. Together, these findings indicate that lake resistomes are regularly stocked with resistance genes evolved in the context of both veterinary and human antibiotics use and represent reservoirs of ARGs that require further monitoring.

The occurrence of potentially pathogenic fungi and protists in Canadian lakes predicted using geomatics, in situ and satellite-derived variables: Towards a tele-epidemiological approach.

Eukaryotic pathogens including fungi and enteroparasites infect humans, animals and plants. As integrators of landscape catchment, lakes can reflect and record biological and geochemical events or anthropogenic changes and provide useful knowledge to formulate public health, food security and water policies to manage and prevent diseases. In this context, potentially pathogenic fungi and parasites were sampled using 18S rRNA gene amplicon sequencing in 382 lakes displaying a broad range of sizes and human impact on the watershed in 10 ecozones across Canada. Based on pathogen classifications from the ePATHogen database published by the Public Health Agency of Canada, we identified 23 health-relevant genera for human and animal hosts, including Cryptococcus and Cryptosporidium. Our study investigated the potential of remote sensing and geomatics to predict microbial contamination in a tele-epidemiological approach. We used boosted regression tree modeling to evaluate the probability of occurrence of the most common genera found in our dataset based on 10 satellite-derivable, geomatics and field survey variables which could be potential sources or transport mechanisms through the watershed or survival factors in the water. We found that southern ecozones that possess the highest agricultural and pasture activities tend to contain lakes with the largest number of potential pathogens including several fungi associated with plant diseases. Bio-optical factors, such as colored dissolved organic matter, were highly related to the occurrence of the genera, potentially by protecting against damage from ultraviolet light. Our results demonstrate the capability of tele-epidemiology to provide useful information to develop government policies for recreational and drinking water regulations as well as for food security.

Stability of HTLV-2 antisense protein is controlled by PML nuclear bodies in a SUMO-dependent manner.

Since the identification of the antisense protein of HTLV-2 (APH-2) and the demonstration that APH-2 mRNA is expressed in vivo in most HTLV-2 carriers, much effort has been dedicated to the elucidation of similarities and/or differences between APH-2 and HBZ, the antisense protein of HTLV-1. Similar to HBZ, APH-2 negatively regulates HTLV-2 transcription. However, it does not promote cell proliferation. In contrast to HBZ, APH-2 half-life is very short. Here, we show that APH-2 is addressed to PML nuclear bodies in T-cells, as well as in different cell types. Covalent SUMOylation of APH-2 is readily detected, indicating that APH-2 might be addressed to the PML nuclear bodies in a SUMO-dependent manner. We further show that silencing of PML increases expression of APH-2, while expression of HBZ is unaffected. On the other hand, SUMO-1 overexpression leads to a specific loss of APH-2 expression that is restored upon proteasome inhibition. Furthermore, the carboxy-terminal LAGLL motif of APH-2 is responsible for both the targeting of the protein to PML nuclear bodies and its short half-life. Taken together, these observations indicate that natural APH-2 targeting to PML nuclear bodies induces proteasomal degradation of the viral protein in a SUMO-dependent manner. Hence, this study deciphers the molecular and cellular bases of APH-2 short half-life in comparison to HBZ and highlights key differences in the post-translational mechanisms that control the expression of both proteins.

La réponse interféron de type I est-elle efficace pour contrôler l'infection par HTLV-1 ?

Innate immunity plays a critical role in the host response to a viral infection. In particular, type I interferons (IFN-I) are major effectors of antiviral innate immunity. Herein, interplays between HTLV-1 and the IFN-I response are reviewed. Particular emphasis is put on virus sensing by innate immunity receptors and on anti-HTLV-1 effects of IFN-I. We also discuss HTLV-1-induced alteration of IFN-I function and how IFN-I/AZT treatment of adult T-cell leukemia/lymphoma patients can lead to complete remission despite virus-induced escape mechanisms.